Compression coil spring and method for producing same

Active Publication Date: 2014-10-16
NHK SPRING CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0016]In view of above-mentioned circumstances, an object of the present invention is to provide a compression coil spring and a method for producing same in which generation of residual stress

Problems solved by technology

Here, in a case in which Rz is more than 20 μm, concave parts of the surface roughness may become sources at which stress concentrates, cracking may be generated and spread from the concave parts as origin points, and this may result in premature breakage.
Furthermore, this surface roughness is formed by friction with tools during coiling, and by shotpeening treatment.
There was a problem in dimensional accuracy in Comparative Example 3 that was produced by the production process D. For example, the standard deviation of coil diameter that was evaluated for fifty coil springs after they were tempered, was 0.072 mm,

Method used

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  • Compression coil spring and method for producing same
  • Compression coil spring and method for producing same
  • Compression coil spring and method for producing same

Examples

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Evaluation of Coiling Property

[0062]First, coiling property was evaluated by using a coiling machine (see FIGS. 2 and 3) having a high frequency heating coil. Oil tempered wires, each of them having a wire diameter of 1.0 to 10.0 mm and having chemical component shown in Table 1, were prepared, and they were coiled while heating the wire material at 900° C. by the coiling machine. Coiling was performed under combined conditions of wire diameter d and spring index D / d shown in Table 2.

TABLE 1(wt %)CSiMnCr0.51 to 0.591.20 to 1.600.50 to 0.800.50 to 0.80

TABLE 2Samplesd (mm)D / dCoiling propertyExample 11.06.0IVExample 21.26.0IIIExample 31.56.0IExample 42.06.0IExample 53.06.0IExample 64.02.5IVExample 74.03.0IExample 84.06.0IExample 94.08.0IExample 105.06.0IExample 117.06.0IExample 129.06.0IExample 1310.06.0II

[0063]Evaluation results of coiling property are also shown in Table 2. In Table 2, “I” means that the approximately circular coil spring could be produced without being abnormally de...

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Abstract

A compression coil spring having high durability can be provided by using an inexpensive wire material. The present invention provides a compression coil spring formed by using a steel wire material, the steel wire material made of C: 0.45 to 0.85 mass %, Si: 0.15 to 2.5 mass %, Mn: 0.3 to 1.0 mass %, Fe and inevitable impurities as a remainder, and a circle-equivalent diameter of 1.5 to 9.0 mm, wherein hardness of a freely selected cross-section of the wire material is 570 to 700 HV, and at an inner diameter side of the coil spring, unloaded compressive residual stress at a depth of 0.2 mm from a surface in an approximate maximal main stress direction in a case in which compressive load is loaded on the spring is 200 MPa or more, and unloaded compressive residual stress at a depth of 0.4 mm from surface is 100 MPa or more.

Description

TECHNICAL FIELD[0001]The present invention relates to a compression coil spring for use in an engine and clutch of a vehicle, for example, and in particular, relates to a compression coil spring which exhibits superior fatigue resistance even in environments of high stress, and relates to a method for producing the same.BACKGROUND ART[0002]In recent years, it has been progressively required to reduce the fuel consumption of vehicles in view of environmental problems, and reduction in size and weight of parts for vehicles has been also severely required more than ever. To satisfy the requirements for reduction in size and weight, research on strengthening of materials and surface strengthening by a surface treatment have been actively performed in the field of compression coil spring parts such as a valve spring used in an engine or a clutch torsion spring used in a clutch, for example. As a result, fatigue resistance and settling resistance, which are important properties in a coil ...

Claims

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Application Information

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IPC IPC(8): F16F1/02C21D9/02F16F1/06
CPCF16F1/021C21D9/02F16F1/06B21F35/00C21D7/06C21D8/065C22C38/02C22C38/04C22C38/18C22C38/24C22C38/34C22C38/46C21D2211/008B24C1/10
Inventor IKAI, KAZUYASHIRAISHI, TOHRUONO, YUICHIROONO, YOSHIKI
Owner NHK SPRING CO LTD
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